Allergic rhinitis, known as hay fever, is caused by pollens of specific seasonal plants, airborne chemicals and dust particles in people who are allergic to these substances. It is characterized by sneezing, runny nose and itching eyes. This seasonal allergic rhinitis is commonly known as 'hay fever', because it is most prevalent during haying season. It is particularly prevalent from late May to the end of June (in the Northern Hemisphere). However, it is possible to suffer from hay fever throughout the year. The time of year at which hay fever symptoms manifest themselves varies greatly depending on the types of pollen to which an allergic reaction is produced. The pollen count, in general, is highest from mid-spring to early summer. As most pollen are produced at fixed periods in the year, a long-term hay fever sufferer may also be able to anticipate when the symptoms are most likely to begin and end, although this may be complicated by an allergy to dust particles. Treatment of Hay Fever Allergen Immunotherapy Allergen immunotherapy is commonly used in patients suffering from allergic rhinitis, allergic asthma or life threatening stinging insect allergy. This type of therapy has been found to potentially alter the course of all three of the above disorders. Allergen immunotherapy provides long-term relief of the symptoms associated with rhinitis and asthma. "Allergy shots" (Hyposensibilization, immunotherapy) are occasionally recommended if the allergen cannot be avoided and if symptoms are hard to control. This includes regular injections of the allergen, given in increasing doses (each dose is slightly larger than the previous dose) that may help the body adjust to the antigen. Homeopathy It has been claimed that homeopathy provides relief free of side effects. However, this is strongly disputed by the medical profession on the grounds that there is no valid evidence to support this claim. The list of suggested medication includes:

• Arundo mauritanica.
• Galphimia glauca.
• Luffa.

Medication The most appropriate medication depends on the type and severity of symptoms. Specific illnesses that are caused by allergies (such as asthma and eczema) may require other treatments. Options include the following:

• Fast-acting strong antihistamines such as drugs including chlorphenamine which relieve the symptoms after a hay fever "attack".

• Short-acting antihistamines, which are generally over-the-counter (non-prescription), often relieve mild to moderate symptoms, but can cause drowsiness. A pediatrician should be consulted before using these medicines in children, as they may affect learning.

One formerly prescription medication, loratadine (Claritin), is now available over the counter in many countries. It does not tend to cause drowsiness or affect learning in children. Azelastine (Astelin) is the only antihistamine available as a nasal spray.

• Longer-acting antihistamines cause less drowsiness, can be equally effective and usually do not interfere with learning. These medications include fexofenadine (Allegra), and cetirizine (Zyrtec).

• New leukotriene receptor antagonists, such as montelukast (Singulair) and zafirlukast (Accolate) have proven very effective in dealing with allergic rhinitis, without the common side effects of the first-generation antihistamines, such as drowsiness. These medicines are also long-acting, and are recommended to be taken once daily.

• Corticosteroid nasal sprays are effective and safe, and may be effective without oral antihistamines. These medications include fluticasone (Flonase, Flixonase), budesonide (Rhinocort), flunisolide (Syntaris), mometasone (Nasonex), triamcinolone (Nasacort AQ) and beclomethasone (Beconase).

• Topical decongestants may also be helpful in reducing symptoms such as nasal congestion, but should not be used for long periods as stopping them after protracted use can lead to a rebound nasal congestion (Rhinitis medicamentosa).

• Cromolyn sodium (or cromoglycate) is a drug that stabilizes mast cells and prevents their degranulation and subsequent release of histamine. It is available as a nasal spray (Nasalcrom) for treating hay fever. Eye drop versions of cromolyn sodium (Crolom) are available for allergic conjunctivitis.

• A large number of over-the-counter treatments are sold without FDA approval but are known for their positive effects, including herbs like eyebright (Euphrasia officinalis), nettle (Urtica dioica) and bayberry (Myrica cerifera), which have not been shown to reduce the symptoms of nasal-pharynx congestion.

In addition, feverfew (Tanacetum parthenium) and turmeric (Curcuma longa) has been shown to inhibit phospholipase A2, the enzyme which releases the inflammatory precursor arachidonic acid from the bi-layer membrane of mast cells (the main cells which respond to respiratory allergens and lead to inflammation) but this is only in test tubes and it is not established as anti-inflammatory in humans. Kinds of Hay Fever When an allergen such as pollen or dust is inhaled by a person with a sensitized immune system, it triggers antibody production. These antibodies mostly bind to mast cells, which contain histamine. When the mast cells are stimulated by pollen and dust, histamine (and other chemicals) are released. This causes itching, swelling and mucus production. As such, the two categories of allergic rhinitis include:

• Seasonal: occurs particularly during pollen seasons. Seasonal allergic rhinitis does not usually develop until after 6 years of age.

• Perennial: occurs throughout the year. This type of allergic rhinitis is commonly seen in younger children.

Causes of Hay Fever As noted above, hay fever involves an allergic reaction to pollen. A virtually identical reaction occurs with allergy to mold, animal dander, dust and similar inhaled allergens. Particulate matter in polluted air and chemicals such as chlorine and detergents, which can normally be tolerated, can greatly aggravate the condition. The pollens that cause hay fever vary from person to person and from region to region; generally speaking, the tiny, hardly visible pollens of wind-pollinated plants are the predominant cause. Pollens of insect-pollinated plants are too large to remain airborne and pose no risk. Examples of plants commonly responsible for hay fever include:

• Trees: such as birch (Betula), alder (Alnus), hazel (Corylus), hornbeam (Carpinus), horse chestnut (Aesculus), willow (Salix), poplar (Populus), plane (Platanus), linden/lime (Tilia) and olive (Olea). In northern latitudes, birch is considered to be the most important allergenic tree pollen, with an estimated 15–20% of hay fever sufferers sensitive to birch pollen grains. Olive pollen is most predominant in Mediterranean regions.

• Grasses (Family Poaceae): especially ryegrass (Lolium sp.) and timothy (Phleum pratense). An estimated 90% of hay fever sufferers are allergic to grass pollen.

• Weeds: ragweed (Ambrosia), plantain (Plantago), nettle/parietaria (Urticaceae), mugwort (Artemisia), Fat hen (Chenopodium) and sorrel/dock (Rumex)

In addition to individual sensitivity and geographic differences in local plant populations, the amount of pollen in the air can be a factor in whether hay fever symptoms develop. Hot, dry and windy days are more likely to have increased amounts of pollen in the air than cool, damp and rainy days when most pollen is washed to the ground. Prevention of Hay Fever

• Avoiding exposure to pollen is the best way to decrease allergic symptoms.

• Remain indoors in the morning and evening when outdoor pollen levels are highest.

• Wear face masks designed to filter out pollen if you must be outdoors.

• Keep windows closed and use the air conditioner if possible in the house and car.

• Do not dry clothes outdoors.

• Avoid unnecessary exposure to other environmental irritants such as insect sprays, tobacco smoke, air pollution, and fresh tar or paint.

• Avoid mowing the grass or doing other yard work, if possible. Avoid fields and large areas of grassland.

• Regular hand- and face-washing removes pollen from areas where it is likely to enter the nose.

• A small amount of petroleum jelly around the eyes and nostrils will stop some pollen from entering the areas that cause a reaction

• Avoid bicycling or walking; instead use a method of confined transportation such as a car.

• Wear sunglasses, which reduce the amount of pollen entering the eyes.

In any case, now that you know most everything there is to know about hay fever, your respiratory health will be safe once again. Just remember to make use of these tips and information before it's too late.